Re: Canonical format max amp limits?
Re: Canonical format max amp limits?
- Subject: Re: Canonical format max amp limits?
- From: Mark Cookson <email@hidden>
- Date: Thu, 15 Jul 2004 09:10:01 -0500
On Jul 14, 2004, at 6:42 PM, Steve Checkoway wrote:
Actually, in my case, I am doing fairly trivial DSP. I get my data as
16 bit signed integer since that is what both the windows code and the
linux code expect. Using the ancient Sound Manager, I could just pass
that data right through to the sound card since at least mine and
every other one that I've encountered supports 16 bit int at the very
least. Using CoreAudio, I have to convert it to float. Of course,
CoreAudio must eventually convert this back to int to send to the card
(or whatever you call it when it's builtin, device I suppose). This
step seems unnecessary but I cannot set the input procedure format to
the one I want so I am forced to convert it before passing it along.
For AppleUSBAudio and AppleOnboardAudio, you can send them integer
16-bit (or 24-bit) values, but you have to select the non-mixable
format that the driver publishes. When you do that, the drivers expect
the chosen format and not floats. When the format is mixable, the
driver expects floating point values.
That might eliminate the need for you to convert to floating point and
the driver to convert it back. Unless of course, your DSP code
requires floating point values (some work with fixed point values).
--
Mark Cookson
M-Audio
225 Locust St.
Hudson, WI 54016
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